高产5-氨基乙酰丙酸光合细菌株hemA基因的克隆与序列分析  

Cloning and sequence analysis of hemA from a strain of photosynthetic bacteria with high-yield production of 5-aminolevulinic acid

作　　者：孙勇[1] 吴任[1] 章力[2] 李慕婵[1] 雷腊梅[1] 谢数涛[1] 

机构地区：[1]暨南大学生命科学与技术学院水生生物研究所,广东广州510632 [2]中山大学生命科学学院,广东广州510275

出　　处：《暨南大学学报（自然科学与医学版）》2007年第5期518-523,共6页Journal of Jinan University(Natural Science & Medicine Edition)

基　　金：暨南大学人才科研启动基金资助项目(No.51204019)

摘　　要：对从不同生态环境中分离得到的20株光合细菌,进行5-氨基乙酰丙酸(5-ALA)的产量检测,结果显示一株分离自广州市云溪公园池塘底泥的菌株R5,其5-ALA产量最高,达4.92 mg/L.根据GenBank上公布的5-氨基乙酰丙酸合成酶hemA基因序列,设计引物进行hemA基因的克隆.结果表明,菌株R5的hemA基因序列长1230 bp,不含HindⅢ酶切位点,G+C为64.68%,编码一个409个氨基酸的酶蛋白,分子质量为44.9 ku,与Rho-dopseudomonas palustrisKUGB306菌株的hemA基因序列相似性为98.6%,氨基酸序列相似性为100%.系统发生树显示,菌株R5与Rhodopseudomonas palustris处在一个分支,显示菌株R5可能是Rhodopseudomonas palustris,这与微生物鉴定实验的结果一致.本研究克隆的高产5-氨基乙酰丙酸菌株的hemA基因,为后期获取高产5-ALA的基因工程菌打下基础.5-aminolevulinic acid （5-ALA） is a derivative of 5-carbon amino acid and is found in most living organisms with photosynthetic bacteria having the highest extra-cellular production of 5-ALA. In this study, the productions of 5-ALA by 20 photosynthetic bacteria strains from different habitats were determined. Strain R5 isolated from the bottom mud of a pond in Yunxi park, Guangzhou, had the highest production of 5-ALA （4. 92 mg/L）. 5-aminolevulinate synthase （ALAS）, the first enzyme of the heme biosynthesis pathway, is encoded from hemA gene in photosynthetic bacteria. The full-length sequence of hemA from Strain R5 was 1230 bp, with G ＋ C content of 64.68% and no Hind m restriction enzyme site. It encoded an enzyme of 409 amino acids with a predicted molecular mass of 44.9 kDa. The strain R5 showed 98.6% similarity of nucleotide acid sequence and 100% identity of deduced amino acid sequence with Rhodopseudomonas palustris KUGB306. A phylogenetic tree constructed by the Neighbour-Joining method based on the sequence of ALAS amino acid sequence showed that strain R5 was clustered with Rhodopseudomonas palustris with homology being 100%. Strain R5 with the highest production of 5- ALA should therefore be classified in the genus of microbiological identification. The work lays the overproduction of 5-ALA. Rhoclopseudomonas, which was accordance with the result the foundation for obtaining genetic engineering strains for

关 键 词：5-氨基乙酰丙酸 光合细菌 沼泽红假单胞菌 HEMA 

分 类 号：Q31[生物学—遗传学]